Duplex propeller



S. K. SHERWOOD.

DUPLEX PROPELLER.

APPLICATION FILED MAR. 28,

Patented Feb. '10, 1920.

N V ENTOR. x12/S era/aad ITA/135555. x

STARR K. SHERWOOD, F SEATTLE, WASHINGTON.

DPLEX PROPELLEE.

Specification fof Letters Patent.

Patented Feb. 10, 1920'.

Application filed March 28, 1919. Serial No. 285,796.

To all/whom 1f/may concern.'

Be it known that I, STARR K. SHERwooD, a citizen of the United States, residing at Seattle, in the county of King and State of Washington, haveinvented certain newand useful Improvements in Duplex Propellers,

of which the following is a specification.

The invention relates to propelling means for a craft designed for navigating the air and the water and has for its object to provide means embodying independent propellers coaxially mounted and adapted to be driven in opposite directions at the same or different speeds according to the particular lformation of the propellers and the result to be attained.

The invention consists of two propellers coaxially mounted and disposed as closeto gether as possible to prevent interference and gearing for rotating the propellers 1n opposite directions, the parts being mounted in a novel manner to insure compactness of structure and positive operation.

The drawing illustrates a preferred embodiment of the invention. However, it is to be understood that in adapting the same to meet different conditions, various changes in the form, proportion, and minor details of construction may be resorted to without departing from the nature of the invention as claimed hereinafter.

In the drawing hereto attached,

Figure 1 is a side view of a duplex propeller embodying the invention, parts being in section to show more clearly their relative arrangements.

Fig. 2 is a section on the line 2-2 of Fig. l looking to the right showing the parts on a larger scale. l

Fig. 3 is a front view of the inner or forward propeller.

Corresponding and like parts are referred to in the following description 'and indicated in the several views of the drawing by like reference characters.

A and B represent two Propellers, each of the type embodying a hub and spirally formed blades. These propellers are disposed in close relation and are mounted coaxiallyv and have the inclination of their blades reversely disposed so that both propcllers may coperate when in operation. The reverse inclination of the blades is necessary because the propellers in operation are. rotated in opposite directions. The pitch of the. blades may be the same or vary. By

. having the propellers coaXially mounted and adapted to be reversely driven they have a balancing tendency, thereby avoiding the necesslty for compensating for any torsional movement of the craft and which is more susceptible in aeroplanes.

' A shaft 1 has the propeller A secured thereto and is adapted to be connected with the engine or source of driving power. A bevel gear 2 is keyed or otherwise secured to the shaft 1 to rotate therewith. Oppositely.disposed bevel gears 3 are in mesh with the bevel gear 2 at diametrically oppos1te points, hence are rotated in opposite directions when the bevel gear 2 is drivem/A bevel gear 4l is connected to the hub of the propeller B and is in mesh with the bevel gears 3 at diametrically opposite points. It will thus be understood that the bevel gears 2 and i are rotated in opposite directions and in consequence the propellers A and B are likewise driven in opposite directions. A bearing 5 receives the shaft 1 and the propeller B and is of tubular form. A housing 6 incloses the earing and is connected with the bearing 5 y means of a cross piece or bridge 7 as shown most clearly in Fig. 2. The wall of the housing 6 adjacent the propeller B is inturned, as indicated at 8 to fit within an annular groove formed in the bevel gear 4, thereby preventing any play of the coperating parts. The bevel gears 3 are journaled in the housing 6 and bearing 5, as indicated most clearly in Fig. 2. To reduce the friction to the smallest amount possible the rotating parts may be babbitted or provided with roller bearings in a manner wellunderstood, but which are not indicated as they form no part of the invention.

The forward propeller sets the air or water in motion and the propeller in the rear' rotating in an opposite direction to the forward propeller obtains a purchase on the air or water and supplements the actionv of the forward propeller in advancing the aeroplanes, boat or other craft to which the propeller is applied. The propellers rotating in opposite directions have a balancing effect while at the same time supplementing the action of each other. The housing besides supporting the gear also prevents foreign matter from reaching the parts and may contain a lubricant whereby to cause the gearing and bearings to operate with the least wear and friction.

The foregoing description and the drawing have reference to what may be considered the preferred, or approved form of my invention. It is to be understood that I may make such changes in construction and arrangement and combination of parts, materialsdimensions, et cetera, as may prove expedent and fall Within the scope of the appended claim.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is In combination, a bearing, a propeller mounted on the bearing, a bevel gear secured to the propeller and having an annular groove, a shaft mounted in the bearing, va

propellersecured to the shaft, a bevel gear keyed on the shaft, a housing inelosng the bevel gears and having a Wall fitting the annular groove of the bevel gear rotatable with the propeller' mounted on said bearing and bevel gears Within the housing and journaled thereto and to the said bearing and in mesh With the bevel gearskeyed to the shaft and rotatable with the propeller mounted on the aforesaid bearing.

Intestimony whereof I aiiX my signature in presence of two Witnesses.-

M STARR K. SHERWOOD. 

